1. Field of the Invention
The present invention relates to an implantable cardiac stimulating device of the type having the capability to sense and stimulate the right atrium, to sense the left atrium, and to sense and stimulate the right and left ventricles, respectively.
2. Description of the Prior Art
Most pacers are arranged to stimulate the right ventricle of the heart, but it is also known to stimulate the left ventricle. In particular for the treatment of congestive heart failure or other severe cardiac failures it is known to stimulate the left ventricle, or both ventricles, in order to optimize the hemodynamic performance of the heart.
U.S. Pat. No. 5,720,768 describes different possible electrode positions in order to stimulate or sense the different chambers of the heart. It is also disclosed that the conduction time from right atrium to left atrium may be observed and the left atrium may be paced if the conduction time is too long.
It is well known in the art that it is difficult to position an electrode to pace and sense the left atrium. There is a need to provide a device alleviating these difficulties.